Organic insulating film, manufacturing method thereof, semiconductor device using such organic insulating film and manufacturing method thereof

ABSTRACT

The dielectric constants of SiC and SiCN that are currently the subjects of much investigation are both 4.5 to 5 or so and that of SiOC, 2.8 to 3.0 or so. With further miniaturization of the interconnection size and the spacing of interconnections brought about by the reduction in device size, there have arisen strong demands that dielectric constants should be further reduced. Furthermore, because the etching selection ratio of SiOC to SiCN as well as that of SiOC to SiC are small, if SiCN or SiC is used as the etching stopper film, the surface of the metal interconnection layer may be oxidized at the time of photoresist removal, which gives rise to a problem of high contact resistance. The present invention relates to an organic film made of one of SiOCH, SiCHN and SiCH that is formed using, as a source, a polyorganosilane whose C/Si ratio is at least 5 or greater and molecular weight is 100 or greater, and a semiconductor device wherein such an organic insulating film is used, and more particularly to a semiconductor device having a trench structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. application Ser. No.10/748,821, filed Dec. 30, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic insulating film and asemiconductor device therewith and, more particularly, to alow-dielectric-constant organic insulating film and a manufacturingmethod thereof as well as a semiconductor device with a multi-layeredinterconnection structure wherein such a low-dielectric-constant organicinsulating film is used for an interlayer insulating film and amanufacturing method thereof.

2. Description of the Related Art

In fabrication of the ICs (Integrated Circuits), accompanying advance inthe speed of operation and the degree of integration in the device,further reduction in the device design rule has been in progress. Theminiaturization of the interconnection size and the spacing of theinterconnections made through such reduction in device size tend toincrease the interconnection resistance and the capacitance betweeninterconnections in inverse proportion thereto. Since these increases ininterconnection resistance and capacitance between interconnectionsraise the RC time constant, the signal velocity is lowered, giving riseto a serious problem with respect to attaining higher speeds ofoperations in the device.

Accordingly, the reduction of the interconnection resistance and thecapacitance between interconnections has become a matter of utmostimportance to speed up operations in the device. With the object ofreducing the interconnection resistance, the technique wherein copperhaving a lower electrical resistivity than aluminium hitherto widelyused is employed as the interconnection material and the productsmanufactured therewith have become spreading.

Further, because the capacitance between interconnections increases inproportion to the area of interconnection and the dielectric constant ofthe insulating film separating interconnections and in inverseproportion to the distance between interconnections, for the sake ofreducing the capacitance between interconnections without making anychange in the device design, for instance, the use of an insulating filmhaving a lower dielectric constant than the conventional oxide film(SiO₂) and nitride film (SiN) has been, for example, being muchinvestigated.

When Cu is used for the interconnection material, owing to thedifficulty Cu has in microfabrication with dry etching, a damasceneinterconnection structure such as shown in FIG. 1 is, in general, widelyemployed.

In the method of forming a damascene interconnection, an etching stopperfilm SiN insulating film 003 having an excellent etching selectivity toan interconnection trench SiO₂ interlayer insulating film 0002 that isto be formed subsequently, is first grown, on an underlying SiO₂interlayer insulating film 0001, to a thickness of 50 nm to 150 nm bythe parallel plate type plasma CVD (Chemical Vapor Deposition) methodwith SiH₄, NH₃ and N₂, and an interconnection trench SiO₂ interlayerinsulating film 0002 is then grown to a thickness of 400 nm to 1000 nmor so. Next, a trench pattern is formed by means of photolithography anddry etching, and thereafter the resist pattern is removed by means of O₂dry ashing and wet peeling-off. Using the sputtering technique andplating technique, the trench pattern is then filled up with Cu as wellas a barrier metal such as Ta or TaN which is used to prevent the Cudiffusion and superfluous portions of the Cu and the barrier metal laidon the interconnection trench SiO₂ interlayer insulating film 0002 areremoved by the CMP (Chemical Mechanical Polishing) to form a Cuinterconnection 0007.

In the case that an interlayer insulating film is formed after thedamascene interconnection formation, because Cu is liable to react withSiO₂ to diffuse out, a via plug SiO₂ interlayer insulating film 0010 isnormally grown after a SiN film 0012 is grown on the Cu as adiffusion-prevention insulating film (barrier insulating film) to athickness of 50 nm to 100 nm or so by the parallel plate type plasma CVDmethod using SiH₄, NH₃ and N₂.

Hereat, SiN not only prevents the Cu diffusion but also acts as ametching stopper layer for the SiO₂ film so that the Cu surface may beprevented from being exposed to the atmosphere of SiO₂ etching at thetime of the trench etching for the Cu and the atmosphere of O₂ resistashing at the time of forming a via hole above a damasceneinterconnection of Cu. SiN is, in effect, required to work forprevention of the diffusion and, at the same time, function as anetching stopper layer.

In recent years, for the purpose of reducing the parasitic capacitancebetween interconnections further, there have been widely investigatedthe use of an organic insulating film of SiOF, SiOC or such, which has alower dielectric constant than that of a conventional SiO₂ film of 4.1,together with the use of an organic insulating film of SiC or SiCN witha dielectric constant of 4.5 to 5 or so, formed by the parallel platetype plasma CVD method using, as a source, 4MS (tetramethylsilane) or3MS (triethylsilane) which has a lower dielectric constant than that ofSiN of 7.

FIGS. 15(a) to 16(c) illustrate a conventional method in which SiC filmsor SiCN films grown conventionally using 3MS as a source gas areemployed.

After forming a first Cu interconnection 805, a second SiCN film 806 isgrown, using the afore-mentioned gas. Next, a second SiOC film 807 and athird SiCN film 808 are formed, in the same way, using theafore-mentioned gas and, thereon, a third SiOC film 809 and a secondSiO₂ film 810 are grown.

As shown in FIG. 15(a), using, as a mask, a photoresist where a resistpattern for via hole is formed, etching is applied onto the second SiO₂film 810, the third SiOC film 809, the third SiCN film 808 and thesecond SiOC film 807 to be terminated above the second SiCN film 806.

However, there are occasions in which the etching selection ratiobetween SiOC and SiCN is small so that the etching proceeds to theinterconnection lying in the lower layer as shown in FIG. 15(b). In thatcase, when ashing by O₂ gas is thereafter carried out to peel off thephotoresist, an oxide layer 831 of Cu is formed in a region where the Cuinterconnection has been subjected to the etching. The same also happenswhen a film of either of SiOC and SiC is utilized.

Next, as shown in FIG. 15(c), after applying a coating of ananti-reflection coating film thereto, a second resist pattern for trenchinterconnection 819 is formed through a photoresist 818.

As shown in FIG. 15(d), using the photoresist 818 as a mask, etching isapplied to the second SiO₂ film 810 and the third SiC film 808. Afterthat, the photoresist 818 is peeled off by oxygen ashing, which mayresult in further oxidation of the afore-mentioned oxide layer 831 ofCu, and thereafter the organic peeling-off is carried out.

With the entire surface etch-back, the second SiCN film 806 is thenetched away, as shown in FIG. 16(a). Next, as shown in FIG. 16(b), aftera second Ti/TiN film 820 is formed, a second Cu film 821 is formed.Subsequently, the metal other than the trench interconnection is removedto form a second Cu interconnection 832. Thereon, a fourth SiCN film 822is formed, as shown in FIG. 16(c).

The SiC film, the SiCN film and the SiOC film formed by the parallelplate type plasma CVD method using, as a source material, 4MS(tetramethylsilane) or 3MS (trimethylsilane) are currently under wideinvestigation. The dielectric constants for SiC and SiCN are 4.5 to 5 orso, and the dielectric constant for SiOC is 2.8 to 3.0 or so.

With further miniaturization of the interconnection size and the spacingof interconnections brought about by the reduction in device size, therehave arisen strong demands that dielectric constants should be furtherreduced.

Furthermore, because the etching selection ratio of SiOC to SiCN as wellas that of SiOC to SiC are small, if SiCN or SiC is used as the etchingstopper film, the surface of the metal interconnection layer may beoxidized at the time of photoresist removal, which gives rise to aproblem of high contact resistance.

SUMMARY OF THE INVENTION

The present invention relates to an organic insulating film with a lowdielectric constant that can be advantageously used in a semiconductordevice and a semiconductor device in which such an organic insulatingfilm is utilized.

An organic insulating film with a low dielectric constant of the presentinvention is an organic insulating film formed using, as a source, apolyorganosilane whose C/Si ratio is, at least, equal to or greater than5 and, at the same time, molecular weight is equal to or greater than100. This organic insulating film is grown by the plasma CVD methodusing a polyorganosilane with a molecular weight of 100 or higher as asource.

The polyorganosilane is preferably one or more types ofpolyorganosilanes selected from the group consisting oftrimethylvinylsilane, triethlvinylsilane, dimethyldivinylsilane,diethyldivinylsilane, methyltrivinylsilane, ethyltrivinylsilane,tetravinylsilane, tetraethylsilane and triethylsilane.

Further, the organic insulating film preferably contains a C═C bond, andmoreover the presence of a vinyl group is known to improve the heatresistance thereof.

Hereat, the polyorganosilane that is to be used as a source preferablycontains a vinyl group, at least, in its part. Such a polyorganosilanecontaining a vinyl group, at least, in its part is preferably one ormore types of polyorganosilanes selected from the group consisting oftrimethylvinylsilane, triethlvinylsilane, dimethyldivinylsilane,diethyldivinylsilane, methyltrivinylsilane, ethyltrivinylsilane andtetravinylsilane.

Especially in the case of the SiOH film, an oxidizing agent, an inertgas and a polyorganosilane whose C/Si ratio is at least equal to orgreater than 5 and, at the same time, molecular weight is equal to orgreater than 100 are required as the source gases. The inert gas can beany one of helium, argon and xenon, and the oxidizing agent can be anyone selected from the group consisting of O₂, O₃, H₂O, CO and CO₂.

The oxidizing agent can be an oxidizing gas containing nitrogen, butthis gas is not suitable for the novolak-based photoresist which iscurrently in wide use.

The polyorganosilane that is to be used as the source may be one or moretypes of polyorganosilanes selected from the group consisting oftrimethylvinylsilane, triethlvinylsilane, dimethyldivinylsilane,diethyldivinylsilane, methyltrivinylsilane, ethyltrivinylsilane,tetravinylsilane, tetraethylsilane and triethylsilane, but, from theviewpoint of improving the heat resistance, the presence of a vinylgroup therein is preferable.

In the case of the SiCH film, the source gases are an inert gas that isone of helium, argon and xenon, and a polyorganosilane whose C/Si ratiois, at least, equal to or greater than 5 and, at the same time,molecular weight is equal to or greater than 100. In this case, too, thepolyorganosilane may be one or more types of polyorganosilanes selectedfrom the group consisting of trimethylvinylsilane, triethlvinylsilane,dimethyldivinylsilane, diethyldivinylsilane, methyltrivinylsilane,ethyltrivinylsilane, tetravinylsilane, tetraethylsilane andtriethylsilane, and, especially if it contains a vinyl group, the heatresistance can be improved.

The source gases for the SiCHN film are a nitrogen containing gas, aninert gas that is one of helium, argon and xenon, and a polyorganosilanewhose C/Si ratio is, at least, equal to or greater than 5 and, at thesame time, molecular weight is equal to or greater than 100. Examples ofthe nitrogen containing gas include ammonia, N₂ and hydrazine. Thepolyorganosilane may be one or more types of polyorganosilanes selectedfrom the group consisting of trimethylvinylsilane, triethlvinylsilane,dimethyldivinylsilane, diethyldivinylsilane, methyltrivinylsilane,ethyltrivinylsilane, tetravinylsilane, tetraethylsilane andtriethylsilane, and, especially if it contains a vinyl group in itspart, the heat resistance can be improved.

In the conventional semiconductor device, normally a SiOCH film cansubstitute for a SiO₂ film, and a SiCH film or a SiCHN film, for a SiNfilm.

For application of the organic insulating film of the present inventionto semiconductor devices, the semiconductor integrated circuit devicewith a multi-layered structure is a good candidate for that. Thesemiconductor device with a trench interconnection structure that has,following the progress in miniaturization, started gaining ground is, inparticular, well suited.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic cross-sectional view in explaining a damascenestructure.

FIG. 2 is a schematic cross-sectional view showing a structure accordingto First Embodiment of the present invention.

FIGS. 3(a)-3(d) are a series of schematic cross-sectional viewsillustrating the first process flow in a single damascene methodaccording to the present invention.

FIGS. 4(a)-4(d) are a series of schematic cross-sectional viewsillustrating the second process flow in the single damascene methodaccording to the present invention.

FIGS. 5(a)-5(d) are a series of schematic cross-sectional viewsillustrating the third process flow in the single damascene methodaccording to the present invention.

FIGS. 6(a)-6(c) are a series of schematic cross-sectional viewsillustrating the fourth process flow in the single damascene methodaccording to the present invention.

FIG. 7 is a schematic cross-sectional view showing a structure accordingto Second Embodiment of the present invention.

FIGS. 8(a)-8(d) are a series of schematic cross-sectional viewsillustrating the first via hole first process flow in a dual damascenemethod according to the present invention.

FIGS. 9(a)-9(c) are a series of schematic cross-sectional viewsillustrating the second via hole first process flow in the dualdamascene method according to the present invention.

FIGS. 10(a)-10(d) are a series of schematic cross-sectional viewsillustrating the first middle first process flow in a dual damascenemethod according to the present invention.

FIGS. 11(a)-11(d) are a series of schematic cross-sectional viewsillustrating the second middle first process flow in the dual damascenemethod according to the present invention.

FIGS. 12(a)-12(d) are a series of schematic cross-sectional viewsillustrating the first trench first process flow in a dual damascenemethod according to the present invention.

FIGS. 13(a)-13(d) are a series of schematic cross-sectional viewsillustrating the second trench first process flow in the dual damascenemethod according to the present invention.

FIG. 14 is a series of schematic cross-sectional views illustrating thethird trench first process flow in the dual damascene method accordingto the present invention.

FIGS. 15(a)-15(d) are a series of schematic cross-sectional viewsillustrating the first via hole first process flow in a conventionaldual damascene method.

FIGS. 16(a)-16(c) are a series of schematic cross-sectional viewsillustrating the second via hole first process flow in the conventionaldual damascene method.

FIG. 17 is a schematic cross-sectional view in explaining the structureof the parallel plate type plasma CVD system used in the presentinvention.

FIG. 18 is a graphical representation showing the dielectric constantsof the SiOCH films formed with various gases.

FIG. 19 is a graphical representation showing the dielectric constantsof the SiCH films formed with various gases.

FIG. 20 is a graphical representation depicting the density and thecomposition of the SiCH film as a function of the molecular weight ofthe source gas.

FIG. 21 is a graphical representation showing the etching selectionratios of the SiOCH film with respect to the SiCHN film.

FIG. 22 is a graphical representation showing the comparison of the viahole chain yields between the present invention and the prior art.

FIG. 23 is a graphical representation showing the comparison of thevariations of the interconnection resistances between the presentinvention and the prior art.

DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS

A structure and a manufacturing method of an organic insulating filmthat is a preferred embodiment of the present invention are describedbelow.

In order to reduce the dielectric constant of the organic insulatingfilm, the C/Si composition ratio in the film must be set higher thanthat of a conventional film of SiC, SiCN or SiOC, and this leads to theuse of a source gas which has a larger C/Si composition ratio than 4MSor 3MS.

On the other hand, when the C/Si ratio in the film is set high, the C—Cbonds tend to appear in the film, and, the bond energy of the C—C bondsbeing smaller than the bond energy of the Si—O, Si—C or Si—N bonds, theC—C bonds may be easily broken down and, thus, the film of this sort mayhave a low heat resistance. To increase the heat resistance, it iseffective to make a film contain the C═C bonds whose bond energy ishigher than that of C—C bonds.

The organic insulating film with C═C bonds can be certainly formed bykeeping the electric power or such for the plasma CVD under control butthe use of a source gas which contains bonds of the vinyl group thereinis more effective.

As for a method of lowering the dielectric constant of a film of SiCH,SiCHN or SiOCH, a reduction of the film density is effective. To reducethe film density, a material having a larger molecular weight than 4MS(tetramethylsilane) or 3MS (trimethylsilane) must be utilized, andbesides the deposition must be made with a reduced plasma density sothat the decomposition of the source gas in gas phase may be wellsuppressed.

Accordingly, the present invention provides films of SiCH, SiCHN andSiOCH each having a lower dielectric constant than conventional films ofSiCH, SiCHN and SiOCH.

Further, the present invention relates to a semiconductor device inwhich a film of SiCH, SiCHN or SiOCH having a low dielectric constant isutilized and, more particularly, to a semiconductor layer of this sortwith a trench structure.

Further, referring to FIG. 17, a parallel plate type plasma CVDapparatus utilized in this invention is described below.

The apparatus is provided with an upper electrode 1 and a lowerelectrode 2 within a vacuum tank, and, with a silicon substrate 3 beingset on the lower electrode, the electric power with a high frequencyproduced by a high frequency electric power source 4 is applied onto theupper electrode. Further, it is possible to heat up the lower electrodewith a heater. The apparatus is connected with a gas feeding section 5for supplying the source gas for the apparatus, and a gas dischargingsection 6. The source supplying section is connected, through anencapsulating valve and a mass low controller, to a cylinder of thesource gas, and the structure of the piping in the supplying sectionallows its heating up to 300° C. If a liquid source is employed as itssource, the source supply may be made through a vaporized solutionfeeding apparatus in place of the mass flow controller.

Further, it has been confirmed that, in addition to the parallel platetype plasma CVD, the ECR (Electron Cyclotron Resonance) excited plasmaCVD, the helicon wave excited plasma CVD and the induction coupledplasma CVD can be used to obtain a film of the same excellent quality.

In the first embodiment of the present invention, a SiOCH film isdescribed in detail below.

For a SiOCH film in the first embodiment of the present invention, a Siwafer is disposed in an parallel plate type plasma CVD (referred to asPECVD hereinafter) apparatus and heated to 150 to 400° C., andtrimethylvinylsilane (TMVS), O₂ and H E are fed into the PECVD apparatusat a flow rate of 200 to 2000 sccm (standard cubic centimeters minute),50 to 1000 sccm and 50 to 500 sccm, respectively. The pressure in thechamber is set to be 133 to 1330 Pa and a RF (Radio Frequency) power of200 to 1000 W is applied thereto.

A SiOCH film grown under the above conditions has a C/Si compositionratio of 0.8 to 1.3 and a film density of 1.1 g/cm³ to 1.2 g/cm³. Thisvalue for the C/Si composition ratio is higher and this value for thefilm density, lower, compared with respective values of those of a SiOCHfilm (with a C/Si composition ratio of 0.7 and a film density of 1.3g/cm³) that is grown using trimethylsilane (3MS) as a source gas andwidely utilized as a conventional interlayer insulating film.Accordingly, being 2.2 to 2.7, its dielectric constant provides a lowervalue than the dielectric constant (2.8 to 3.0) of a SiOC film grownusing trimethylsilane (3MS) as a source gas. Further, the refractiveindex of the films grown under the above conditions were found to be ina range of 1.3 to 1.45.

When the deposition of a SiOCH film is carried out with a RF power of400 W or higher, the C/Si composition ratio becomes not less than 0.8but not greater than 1.0, and because the C—C bonds are, in thisinstance, formed within the film, the film becomes thermally unstableand a heat treatment conducted at 400° C. for 30 minutes causes adecrease in film thickness by 5% or so. In contrast with this, when thedeposition is performed with a RF power in a range of 200 to 400 W, theC═C bonds are formed in the film so that the heat resistance isincreased and a decrease in film thickness brought about by a heattreatment conducted at 400° C. for 30 minutes becomes 1% or less.

While in the first embodiment trimethylvinylsilane is used for thesource gas, one type or a combination of two or more types selected fromthe group consisting, for example, dimethyldivinylsilane,diethyldivinylsilane, methyltrivinylsilane, ethyltrivinylsilane,tetravinylsilane, tetraethylsilane and triethylsilane may be employed.

In particular, trimethylvinylsilane, dimethyldivinylsilane,diethyldivinylsilane, methyltrivinylsilane, ethyltrivinylsilane,tetravinylsilane, any of which contains the vinyl group, are preferable.

If a gas such as N₂O or NO₂ is used as an oxidizing gas, a very smallamount of N elements left in the SiOCH film may make up amine groups.Once amine groups are formed in the film, the use of a novolak-basedphotoresist leads to faulty exposure, since the amine group react withthe photoresist, and therefore such an oxidizing gas as containingnitrogen cannot be used.

Next, in the second embodiment of the present invention, a SiCH film isdescribed below.

In the present embodiment, a parallel plate type plasma CVD apparatus isutilized.

With a mass flow controller regulating the flow rates,trimethylvinylsilane is fed thereto at a rate of 300 sccm and H E isconcurrently, at a rate of 1000 sccm. At the time of the filmdeposition, the pressure is set to be 133 Pa to 1330 Pa, the highfrequency electric power, 100 to 400 W and the substrate temperature,350° C.

The measurements of the dielectric constants for the films fabricatedunder the above conditions revealed that their values changecontinuously with the deposition pressure, from a dielectric constant of3.3 for the film grown at 133 Pa to a dielectric constant of 4.2 for thefilm grown at 1330 Pa.

It was vindicated that the dielectric constants for these films can bemade lower than those for the films grown using 3MS or 4MS (thedielectric constants for them are 4.5).

Further, when the films were grown under the above conditions, the C/Sicomposition ratios therein varied in a range of 0.9 to 1.4 and the filmdensities, in a range of 0.9 to 1.4 g/cm³. These results indicate thatthe films are made to have lower densities than the SiCH films (with aC/Si composition ratio of 0.8 and a density of 1.5 g/cm³) grown using3MS, which are considered to bring about reductions of the dielectricconstants.

Further, the refractive indices of the films grown under the aboveconditions vary in a range of 1.70 to 1.85. The results of themeasurements of the FT-IR (Fourier Transform-InfraRed) absorptionspectroscopy indicated the presence of Si—C, Si—CH₃ and Si—H bonds. Onthe other hand, the Si—OH bands resulting from the moisture in the filmwere not detected.

The films were found to have the excellent capability as a barrieragainst Cu, and in the accelerated Cu diffusion test conducted applyinga bias voltage while heating to 450° C., no Cu diffusion was observed.This indicates that these films have the capability equivalent to theconventional SiCH films grown with 3MS.

While, in the examples described so far, trimethylvinylsilane is used asa source, it was established that, in addition to this,triethylvinylsilane, dimethyldivinylsilane, diethyldivinylsilane,methyltrivinylsilane, ethyltrivinylsilane, tetravinylsilane,tetraethylsilane and triethylsilane, every one of which is apolyorganosilane possible to be used as a source having a molecularweight of 100 or greater and a C/Si ratio of 5 or greater, may form afilm of a similar quality. The relationships between the molecularweight of the source compound and the density as well as the C/Sicomposition ratio of the deposited film for the cases that one of theabove sources is used are shown in FIG. 20. It was clearly shown thatthe use of such a source with a molecular weight of 100 or greater and aC/Si ratio of 5 or greater enables to grow a film having a film densityof not less than 1.0 g/cm³ but not greater than 1.4 g/cm³ and a C/Sicomposition ratio of not less than 0.9 but not greater than 1.3.

Further, it has been confirmed that, in addition to the parallel platetype plasma CVD, the ECR excited plasma CVD, the helicon wave excitedplasma CVD and the induction coupled plasma CVD can be used to obtain afilm of the same excellent quality.

Next, as a modified example of the second embodiment, a SiCH filmcontaining vinyl groups therein is described below.

To make vinyl groups contained in the film, it is necessary to preventthe dissociation of the source by the plasma as much as possible. Forthat purpose, the film deposition was made under the conditions that theflow rate of trimethylvinylsilane was as much as 300 sccm or higher andthe plasma electric power was as low as 50 to 100 W.

To examine the presence of vinyl groups in the film, measurements of theinfrared absorption spectroscopy were conducted and the absorptionattributable to vinyl groups was clearly observed in the sample filmgrown under the conditions of a high flow rate and a low high-frequencyelectric power of 50 to 100 W. This occurs because, in plasma with aweak energy, the source may be taken into a film without being brokendown structurally.

Now, it was demonstrated that a SiCH film containing vinyl groups can befabricated by using a source gas linking with vinyl groups and, at thesame time, giving good attention to suppress the decomposition of thesource gas. Further, the amount of vinyl groups taken into the film canbe regulated through a change in plasma electric power, and, if theelectric power is increased to 100 W or higher, vinyl groups becomeabsent in the film.

The heat resistance tests conducted for the films comprising vinylgroups in structure showed that even after the films were heated at 450°C. for 1 hour in the nitrogen atmosphere, the film shrinkages were notexceeding 0.1% and the film characteristics hardly changed. In effect,the vinyl groups taken into the film obviously improve the heatresistance a great deal.

With respect to the dielectric constants, as in the case of containingno vinyl groups, it was found that their values change continuously withthe deposition pressure from a dielectric constant of 3.2 for the filmgrown at 133 Pa to a dielectric constant of 4.2 for the film grown at1330 Pa. In other words, the dielectric constants hardly change with thepresence of vinyl groups in the film. Further, the C/Si compositionratios therein varied in a range of 0.9 to 1.4, while the film densitiesand the refractive indices of the films varied in ranges of 0.9/cm³ to1.4 g/cm³ and 1.70 to 1.85, respectively. In other words, there arehardly any change caused by the presence of vinyl groups in the film.

The films were found to have the excellent capability as a barrieragainst Cu, and in the accelerated Cu diffusion test conducted applyinga bias voltage while heating to 450° C., no Cu diffusion was observed.This indicates that these films have the capability equivalent to theconventional SiCH films grown with 3MS.

While, in the examples described so far, trimethylvinylsilane is used asa source, it was established that, in addition to this,triethylvinylsilane, dimethyldivinylsilane, diethyldivinylsilane,methyltrivinylsilane, ethyltrivinylsilane, tetravinylsilane,tetraethylsilane and triethylsilane, every one of which is apolyorganosilane possible to be used as a source having a molecularweight of 100 or greater and a C/Si ratio of 5 or greater, may form afilm of a similar quality.

Further, it has been confirmed that, in addition to the parallel platetype plasma CVD, the ECR excited plasma CVD, the helicon wave excitedplasma CVD and the induction coupled plasma CVD can be used to obtain afilm of the same excellent quality.

Next, in the third embodiment of the present invention, a SiCHN film isdescribed below.

In the present embodiment, with a mass flow controller regulating theflow rates, trimethylvinylsilane and ammonia are each fed thereto at arate of 300 sccm and H E is, concurrently, fed at a rate of 1000 sccm.At the time of the film deposition, the pressure is set to be 133 to1330 Pa, the high frequency electric power, 100 to 400 W and thesubstrate temperature, 350° C.

With ammonia supplied at a rate of 300 sccm, nitrogen is fed into thefilm and thereby a SiCHN film is formed.

The values of the dielectric constants change continuously with thedeposition pressure, from a dielectric constant of 3.8 for the filmgrown at 133 Pa to a dielectric constant of 4.7 for the film grown at1330 Pa. Further, when the films are grown under the above conditions,the C/Si composition ratios therein vary in a range of 1.0 to 1.3, arange where the carbon content is greater than silicon content, whilethe film densities vary in a range of 1.4 cm³ to 1.6 g/cm³ so that thefilms are made to have lower densities than the SiCHN films (with adensity of 1.7 g/cm³) grown using 3MS.

Further, the refractive indices thereof vary in a range of 1.77 to 1.90.The results of the measurements of the FT-IR absorption spectroscopyindicated the presence of Si—C, Si—CH₃ and Si—H bonds. On the otherhand, the Si—OH bands resulting from the moisture in the films were notdetected.

The films were found to have the excellent capability as a barrieragainst Cu, and in the accelerated Cu diffusion test conducted applyinga bias voltage while heating to 450° C., no Cu diffusion was observed.This indicates that these films have the capability equivalent to theconventional SiCHN films grown with 3MS.

While, in the examples described so far, trimethylvinylsilane is used asa source, it was established that, in addition to this,triethylvinylsilane, dimethyldivinylsilane, diethyldivinylsilane,methyltrivinylsilane, ethyltrivinylsilane, tetravinylsilane,tetraethylsilane and triethylsilane, every one of which is apolyorganosilane possible to be used as a source having a molecularweight of 100 or greater and a C/Si ratio of 5 or greater, may form afilm of a similar quality, even if another nitridation source such ashydrazine is employed in place of ammonia.

Further, it has been confirmed that, in addition to the parallel platetype plasma CVD, the ECR excited plasma CVD, the helicon wave excitedplasma CVD and the induction coupled plasma CVD can be used to obtain afilm of the same excellent quality.

Next, as a modified example of the third embodiment, a SiCHN filmcontaining vinyl groups therein is described below. As in the secondembodiment wherein vinyl groups are contained in the film, the filmdeposition was made under the conditions that the flow rate oftrimethylvinylsilane was increased from 300 sccm to a higher one, andmoreover the plasma electric power was made as low as 50 to 100 W.

To examine the presence of vinyl groups in the film, measurements of theinfrared absorption spectroscopy were conducted and the absorptionattributable to vinyl groups was clearly observed in the sample filmgrown under the conditions of a high flow rate and a low high-frequencyelectric power of 50 to 100 W. This also occurs for the SiCHN film,because, in plasma with a weak energy, the source may be taken into afilm without being broken down structurally.

It was also found that the Si—C, Si—CH₃ and Si—H bonds are all presentin the film. On the other hand, the Si—OH bands resulting from themoisture in the film were not detected.

Meanwhile, when the electric power was increased to 100 W or higher, theabsorption attributable to the vinyl groups disappeared and only theSi—C, Si—CH₃ and Si—H bonds were detected in the film.

It was demonstrated that a SiCHN film containing vinyl groups can befabricated by using a source gas linking with vinyl groups and, at thesame time, giving good attention to suppress the decomposition of thesource gas. Further, it was found that the amount of vinyl groups takeninto the film can be regulated through a change in plasma electricpower.

Further, the heat resistance tests conducted for the films comprisingvinyl groups in structure showed that even after the films were heatedat 450° C. for 1 hour in the nitrogen atmosphere, the filmcharacteristics hardly changed. In effect, the vinyl groups taken intothe film obviously improve the heat resistance a great deal. Further,the values of the dielectric constants change continuously with thedeposition pressure, from a dielectric constant of 3.8 for the filmgrown at 133 Pa to a dielectric constant of 4.7 for the film grown at1330 Pa.

Further, the C/Si composition ratios in the film vary in a range of 1.0to 1.3, a range where the carbon content is greater than siliconcontent, while the film densities and the refractive indices thereofvary in a range of 1.4 g/cm³ to 1.6 g/cm³ and 1.77 to 1.90,respectively. In other words, all of them hardly change with thepresence of vinyl groups in the film. In short, the vinyl groupscontained in the film have the effect of raising the heat resistance ofthe barrier film without increasing the dielectric constantsignificantly. The films were found to have an excellent capability as abarrier against Cu, and, in the accelerated Cu diffusion test conductedapplying a bias voltage while heating to 450° C., no Cu diffusion wasobserved. This indicates that these films have the capability equivalentto the conventional SiCHN films grown with 3MS.

In the present embodiment, trimethylvinylsilane is used as a source, itwas established that, in addition to this, triethylvinylsilane,dimethyldivinylsilane, diethyldivinylsilane, methyltrivinylsilane,ethyltrivinylsilane, tetravinylsilane, tetraethylsilane andtriethylsilane, any one of which is a polyorganosilane possible to beused as a source having a molecular weight of 100 or greater and asource having a C/Si ratio of 5 or greater, can form a film of a similarquality.

Further, it has been confirmed that, in addition to the parallel platetype plasma CVD, the ECR excited plasma CVD, the helicon wave excitedplasma CVD and the induction coupled plasma CVD can be used to obtain afilm of the same excellent quality.

FIGS. 18 and 19 show the dielectric constants of the SiOC films and SiCfilms grown using either of 3MS and 4MS, together with the dielectricconstants of the SiOCH films and SiCH films grown using, as a source,either of TMVS and DMVS whose respective molecular weights are both 100or greater and C/Si ratios, both 5 or greater. Both of the SiOC filmsgrown using either of 3MS and 4MS have a dielectric constant of 2.9,while the SiOC films grown with TMVS and DMVS have dielectric constantsof 2.6 and 2.4, respectively. It is thereby demonstrated that the use ofa source with a large molecular weight allows the film with a lowelectric constant to be formed.

Referring to the drawings, Examples in which an organic insulating filmaccording to a preferred embodiment of the present invention is appliedto a semiconductor device are described below.

EXAMPLE 1

FIG. 2 is a schematic partial cross-sectional view of a semiconductordevice with a single damascene structure of Example 1.

In a semiconductor device shown in FIG. 2, upon an underlying insulatingfilm 201 that covers elements such as MOS (Metal-Oxide-Semiconductor)transistors formed on a Si substrate, layers of a first etching stopperfilm 202, a first SiOCH film 203, a first hard mask film 204, a firstbarrier insulating film 211, a second SiOCH film 212, a second hard maskfilm 213, a second etching stopper film 214, a third SiOCH film 217, athird hard mask film 218 and a second barrier insulating film 223 arelaid in succession.

In layers of insulating films, first copper interconnections 210, secondcopper interconnections 224 and copper plugs 228 each of which connectsa first copper interconnection with a second copper interconnection areformed.

The first copper interconnections 210 are formed in layers of insulatingfilms made of the first etching stopper film 202, the first SiOCH film203 and the first hard mask film 204 which are laid in succession on theunderlying insulating film 201.

The second copper interconnections 224 are formed in layers ofinsulating films made of the second etching stopper film 214, the thirdSiOCH film 217 and the third hard mask film 218.

The copper plugs 228 that connect the first copper interconnectionswhich constitute lower layer interconnections with the second copperinterconnections 224 which constitute upper layer interconnections areformed in a layered film made of the first barrier insulating film 211,the second SiOCH film 212 and the second hard mask film 213, whichfunctions as an interlayer insulating film separating the upper layerinterconnections and the lower layer interconnections.

A part of the first copper interconnection 210 may cut into theunderlying insulating film 201.

Among the interlayer insulating films constituting the above structure,every one of the first and the second barrier insulating films and thefirst and the second etching stopper films can be a SiCH film, a SiCHNfilm or a layered film of a SiCH film and a SiCHN film.

Next, a method of manufacturing the afore-mentioned semiconductor deviceis described below, with reference to a series of schematiccross-sectional views illustrating the steps thereof and shown in FIGS.3(a) to 6(d).

Firstly, as shown in FIG. 3(a), on an underlying insulating film 301, afirst etching stopper film 302, a first SiOCH film 303 and a first hardmask film 304 are grown in succession.

The first etching stopper film 302 can be either a SiCH film or a SiCHNfilm and grown to a thickness of 30 to 150 nm by the parallel plate typeplasma CVD method. The first SiOCH film 303 is grown to a thickness of200 to 1000 nm or so. The first hard mask film 304 is one of SiO₂, SiNand SiON films and grown to a thickness of 50 to 200 nm or so.

Over them, a first photoresist 305 is formed on the first hard mask film304 and a trench pattern 306 is formed by means of photolithography.

Subsequently, as shown in FIG. 3(b), using, as a mask, the firstphotoresist film 305 onto which the trench pattern 306 has beenpatterned, the first hard mask film 304 and the first SiOCH film 303 areetched by means of dry etching, and after the photoresist 305 is peeledoff, the first etching stopper film 302 is removed by the etch backapplied onto the entire surface thereof, whereby a first interconnectiontrench pattern 307 is formed.

Herein, when the first etching stopper film 302 is removed by etching, apart of the underlying insulating film may be removed by etching butthis does not cause any serious problem.

The first etching stopper film 302 can be omitted. In this instance,only the first hard mask film 304 and the first SiOCH film 303 areremoved by etching, with the first photoresist 305 being used as a mask.

Next, as shown in FIG. 3(c), a first barrier metal film 308 and a firstconductive film 309 are formed.

The first barrier metal film 308 is a film made of Ta, TaN, TiN or suchand formed either by the sputtering method of the CVD method. The firstconductive film 309 is either a Cu film or a Cu alloy film and formed bythe sputtering method, the CVD method or the plating method.

After that, as shown in FIG. 3(d), the first barrier metal film 308 andthe first conductive film 309 lying on the hard mask film 304 areremoved by the CMP and thereby first interconnections 310 are formed.

Next, as shown in FIG. 4(a), a first barrier insulating film 311, asecond SiOCH film 312 and a second hard mask film 313 are grown insuccession.

Next, as shown in FIG. 4(b), using a photoresist 315, a resist patternfor via hole 316 is formed thereon by photolithography in the same wayas described above.

Next, the second hard mask film 313 and the second SiOCH film 312 areetched by means of dry etching and the second photoresist 315 is peeledoff (FIG. 4(c)).

After that, the entire surface is subjected to the etch back to make thefirst barrier insulating film 311 open, and thereby a via pattern isformed.

Next, as shown in FIG. 4(a), a second barrier metal film 326 and asecond conductive film 327 are formed.

The second barrier metal film 326 is a film made of Ta, TaN, TiN or suchand formed either by the sputtering method of the CVD method. The secondconductive film 327 is either a Cu film or a Cu alloy film and formed bythe sputtering method, the CVD method or the plating method.

After that, as shown in FIG. 5(a), the barrier metal film 326 and thesecond conductive film 327 lying on the hard mask film 313 are removedby the CMP and thereby first conductive plugs 328 are formed.

After that, as shown in FIG. 5(b), a second etching film 314 is formedthereon.

Further, as shown in FIG. 5(c), a third SiOCH film 317 is formed andthereon a third hard mask film 318 is formed. An anti-reflection coatingfilm 325 is thereon formed and, using a third photoresist 319, a secondresist pattern for interconnection trench 320 is further formed thereon.

As shown in FIG. 5(d), using the third photoresist mask 319, etching forfabrication is applied onto the third hard mask film 318 and the thirdSiOCH film 317, and after peeling off the third photoresist 319, theentire surface thereof is subjected to the etch back to make the secondetching stopper film 314 open in the form of the interconnectionpattern.

The second etching stopper film 314 can be also omitted. On thisoccasion, using the third photoresist 319 as a mask, etching can besimply carried out. However, in this case, because the use of oxygenashing to remove the photoresist may cause oxidation of the coppersurface, the use of an organic solvent is required.

Following that, as shown in FIG. 6(a), a third barrier metal film 321 isformed and then a third conductive film 322 is formed. As shown in FIG.6(b), the third barrier metal film 321 and the third conductive film 322lying on the hard mask film 318 are removed by the CMP and therebysecond interconnections 324 are formed.

As shown in FIG. 6(c), a second barrier insulating film 323 is formed.

By repeating successively the above steps shown from FIG. 4(a) to FIG.6(c), formation of a multi-layered interconnection may be accomplished.

While, in the present example, the upper layer interconnections, thelower layer interconnections and the via plugs to connect the upperlayer interconnections with the lower layer interconnections are allformed of Cu films or Cu alloy films, it is not necessarily required touse Cu or Cu alloy, and silver or a silver containing alloy can be used.Further, a Cu film or a Cu alloy film can be used to form at least onebut not all of the upper layer interconnections, the lower layerinterconnections and the via plugs to connect the upper layerinterconnections with the lower layer interconnections.

Further, a Cu containing alloy may further contain one or more metalsselected from the group consisting of Si, Al, Ag, W, Mg, Be, Zn, Pd, Cd,Au, Hg, Pt, Zr, Ti, Sn, Ni and Fe.

The barrier metal may be made of one or more barrier metals selectedfrom the group consisting of Ti, TiN, TiSiN, Ta, TaN and TaSiN.

The same as described above applies to a dual damascene structuredescribed below.

EXAMPLE 2

Next, as Example 2, a dual damascene structure is described below,referring to a schematic partial cross-sectional view of a dualdamascene structure shown in FIG. 7.

In this semiconductor device, upon an underlying insulating film 401that covers elements such as MOS transistors formed on a Si substrate, afirst etching stopper film 402 is formed to a thickness of 30 to 150 nmand thereon a first SiOCH film 403 is formed to a thickness of 200 to500 nm, and thereon a first hard mask film 404 is further formed thereonto a thickness of 50 to 200 nm, and, in this layered insulating layer,first copper interconnections 410 are formed, and a second barrierinsulating film 411 is formed to a thickness of 30 to 150 nm so as tocover top sections of the copper interconnections. A second SiOCH film412 is thereon formed to a thickness of 200 to 500 nm as an interlayerinsulating film. Further, as an overlying layer thereof, a secondetching stopper film 413 with a thickness of 30 to 150 nm, and a thirdSiOCH film 414 with a thickness of 200 to 500 nm and a second hard maskfilm 417 with a thickness of 50 to 200 nm are formed. In this layeredinsulating film, second copper interconnections 422 are formed, and asecond barrier insulating film 423 is further formed thereon to athickness of 30 to 150 nm.

For the overlying layers, this step is performed repeatedly, andformation of multi-layered interconnections in the dual damascenestructure is accomplished.

The etching stopper film(s) can be omitted in the dual damascenestructure as in the single damascene structure.

Next, referring to the drawings, a method of manufacturing a damascenestructure shown in FIG. 7 is described below.

FIGS. 8(a) to 9(c) are a series of schematic cross-sectional viewsillustrating the steps of a manufacturing method of a damascenestructure according to the via hole first method.

FIGS. 10(a) to 11(d) are a series of schematic cross-sectional viewsillustrating the steps of a manufacturing method of a damascenestructure according to the middle first method.

FIGS. 12(a) to 14 are a series of schematic cross-sectional viewsillustrating the steps of a manufacturing method of a damascenestructure according to the trench first method.

A manufacturing method of a dual damascene structure according to thevia hole first method is described, referring to FIGS. 8(a) to 9(c).

In the same way as shown in FIGS. 3(a) to 3(d), first Cuinterconnections 510 are formed. Next, as shown in FIG. 8(a), a secondSiCHN film 511 is formed and, thereon, a second SiOCH film 512, a thirdSiCHN film 513, a third SiOCH film 514 and a second SiO₂ film 515 areformed, and, overlying them, an anti-reflection coating film 516 isformed. A photoresist 517 is formed thereon and the exposure anddevelopment are made therethrough to form a resist pattern for via hole518.

Next, using the photoresist 517 as a mask, etching is applied onto thesecond SiO₂ film 515, the third SiOCH film 514, the third SiCHN film 513and the second SiOCH film 512, and this etching is stopped by the secondSiCHN film 511. After that, the photoresist 517 is peeled off (FIG.8(b)).

As shown in FIG. 8(c), a coating of an anti-reflection coating film 519is made and, then, a photoresist 520 is made on the anti-reflectioncoating film 519, and then, exposure and development are appliedthereto, whereby a second resist pattern for trench interconnection 521is formed.

As shown in FIG. 8(d), using the photoresist 520 as a mask, etching isapplied onto the second SiO₂ film 515 and the third SiOCH film 514. Thisetching is stopped by the third SiCHN film 513. After that, thephotoresist 520 is removed, and another etch back is carried out to etchthe second SiCHN film 511 and the third SiCHN film 513. Since theetching is hereat made to become slightly overetching, a part of thesecond SiOCH film 512 may be also removed by etching.

As shown in FIG. 9(a), a second Ta/TaN film 522 is then grown andthereafter a second Cu film 523 is grown. As shown in FIG. 9(b), byperforming the CMP, metals other than the trench interconnections areremoved to form second Cu interconnections 524.

Subsequently, as shown in FIG. 9(c), a fourth SiCHN film 525 is grown.

Next, a manufacturing method of a dual damascene structure according tothe middle first method is described, referring to FIGS. 10(a) to 11(d).

In the same way as shown in FIGS. 3(a) to 3(d), first Cuinterconnections 610 are formed. Next, a second SiCH film 611 is formedthereon, and a second SiOCH film 612 is further formed thereon.Overlying them, a third SiCH film 613 is formed (FIG. 10(a)).

As shown in FIG. 10(b), on the third SiCH film 613, a photoresist 614patterned with a resist pattern for via hole 615 is formed.

As shown in FIG. 10(c), using the photoresist 614 as a mask, the thirdSiCH film 613 is etched and, thereafter, an ashing and an organicpeeling-off are conducted. Thereon, a third SiOCH film 616 and a thirdSiO₂ film 617 are formed.

Next, as shown in FIG. 10(d), a photoresist 618 is formed so as to leavea second resist pattern for trench interconnection 619 therein.

As shown in FIG. 11(a), while using, as a mask, the photoresist 618first and then the third SiO₂ film 617, the third SiOCH film 616 and thethird SiCH film 613 one after another as the etching proceeds, thesecond SiOCH film 612 is worked into form. After that, by making theetch back, the second SiCH film 611 is etched.

As shown in FIG. 11(b), a second Ta/TaN film 620 is grown. Further, asecond Cu film 621 is grown. Following that, as shown in FIG. 11(c), themetal other than the trench interconnections is removed by the CMP toform second Cu interconnections 623 and, thereafter, as shown in FIG.11(d), a fourth SiCH film 622 is formed.

Next, a manufacturing method of a dual damascene structure according tothe trench first method is described, referring to FIGS. 12(a) to 14(a).

In the same way as shown in FIGS. 3(a) to 3(d), Cu interconnections 710in a first layer are formed.

Next, as shown in FIG. 12(a), a second SiCH film 711, a second SiOCHfilm 712, a third SiCH film 713, a third SiOCH film 716 and a first SiO₂film 717 are formed. Overlying them, an anti-reflection coating film 725is formed and thereon a photoresist 718 is formed to leave a secondresist pattern for trench interconnection 719. As shown in FIG. 12(b),with the photoresist mask, the first SiO₂ film 717 and the third SiOCHfilm 716 are etched and the third SiCH film 713 stops this etching, and,subsequently, the photoresist is subjected to ashing and then removed bythe organic peeling-off.

As shown in FIG. 12(c), the etch back is applied onto the entire surfacethereof to etch the third SiCH film 713.

Next, as shown in FIG. 12(d), a photoresist 714 is formed to leave aresist pattern for via hole 715 therein.

As shown in FIG. 13(a), using the photoresist 714 as a mask, the secondSiOCH film 712 is etched, and, after the second SiCH film 711 stops theetching, the photoresist 714 is subjected to ashing and removed by theorganic peeling-off. After that, as shown in FIG. 13(b), the etch backis applied onto the entire surface thereof to make the second SiCH film711 open.

As shown in FIG. 13(c), a second Ta/TaN film 720 is grown and thereaftera second Cu film 721 is grown. Subsequently, after the metal other thanthe second copper interconnections is removed by the CMP as shown inFIG. 13(d), a fourth SiCH film 722 is grown thereon as shown in FIG. 14.

In the afore-mentioned Examples 1 and 2, SiCH and SiCHN are hereatequivalent and the substitution does not cause any serious problems.

EXAMPLE 3

Example 3 wherein either of SiCH films and SiCHN films were used for thebarrier insulating films in a semiconductor device is described below.

In a semiconductor device shown in FIG. 2, SiCH films were utilized forthe insulating films 202, 211, 214 and 223.

For these SiCH films, SiCH films containing vinyl groups therein andhaving a dielectric constant of 3.8 were hereat employed. Theexamination of the heat resistance conducted for the obtained layeredstructure at temperatures up to 450° C. showed its excellentcharacteristics without any hint of deterioration in the via hole yieldeven when heated to 450° C. Further, it was found that the effectivedielectric constant was reduced by 10%, compared with a semiconductordevice wherein SiCH films with a dielectric constant of 4.5 which weregrown using 3MS were employed.

In a semiconductor device shown in FIG. 2, SiCHN films that are ThirdEmbodiment were utilized for the insulating films 202, 211, 214 and 223.

For these SiCHN films, SiCHN films containing vinyl groups therein andhaving a dielectric constant of 4.2 were hereat employed. Theexamination of the heat resistance conducted for the obtained layeredstructure at temperatures up to 450° C. showed its excellentcharacteristics without any hint of deterioration in the via hole yieldeven when heated to 450° C. Further, it was found that the effectivedielectric constant was reduced by 10%, compared with a semiconductordevice wherein SiCH films with a dielectric constant of 5 which weregrown using 3MS were employed.

The present invention provides a method of manufacturing a SiOCH film ofhigh quality with a low dielectric constant. Further, the presentinvention can provide a semiconductor device structure which can reducean effective dielectric constant, while maintaining the interconnectionreliability by applying, as a low-dielectric-constant insulating film,the above SiOCH film to a multi-layered interconnection in asemiconductor device.

The present invention can provide respective manufacturing methods of aSiCH and a SiCHN barrier insulating film of high quality with a lowdielectric constant. Further, the present invention can provide asemiconductor device structure which can reduce an effective dielectricconstant, while maintaining the interconnection reliability by applying,as a barrier insulating film, either of the above SiOCH film and SiCHNfilm to a multi-layered interconnection in a semiconductor device.

Further, the obtained films have excellent film quality, and carboncontents in the films are greater than those in conventional SiC filmsand SiCN films, and, as a result, the present invention with the SiCHNfilms can provide higher etching selection ratios than the prior artwith the conventional SiOC films or SiOCH films.

Respective data for the etching selection ratio of the SiOCH film to theSiCHN film according to the prior art and the present invention areshown in FIG. 21. For the etching gas, a CF-based gas was employed. TheSiCN film grown with 3MS and NH₃ and H E has a low carbon content in thefilm so that the etching selection ratio of the SiOC film to the SiCNfilm was as low as 8 and not sufficiently high. In contrast with this,with respect to the SiCHN film that was grown with TMVS, the etchingselection ratio of the SiOCH film obtained was approximately 15 andsatisfactorily high. The yield for a chain of 500,000 via holes with adiameter of 0.2 μm thereat is shown in FIG. 22.

FIG. 22 is a graphical representation of the yields for the via holes inthe dual damascene interconnections formed by the via hole first method.When the conventional SiCN films formed with 3MS were used, the via holeyield was approximately 80%. As against this, when the SiCHN film formedwith TMVS was used, the yield obtained was approximately 98%.

While what is shown herein is the data for the yields of the via holesin the dual damascene interconnections formed by the via hole firstmethod, also in the dual damascene interconnections formed by the middlefirst method, the SiCH film of the present invention, which was formedwith TMVS, provided a higher yield.

Further, FIG. 23 is a graphical representation for the interconnectionresistances in the dual damascene interconnections fabricated by thetrench first method.

Another effect of the present invention was observed on the variation ofthe layer resistance in the film structure wherein the SiCHN film of thepresent invention, which was formed with TMVS, was utilized. Thedecrease in variation of the layer resistance was also brought about bythe improvement of the etching selection ratio with respect to theetching stopper film. As shown in FIG. 23, for the conventional etchingstopper films of the SiCHN films grown with 3MS, the resistances variedfrom 75 to 90Ω, while the variation of the resistances for the SiCHNfilms grown with TMVS in accordance with the present invention wasalmost halved.

1-88. (canceled)
 89. A SiCHN film having a C/Si composition ratio of 1.0to 1.3
 90. A SiCHN film having a density of 1.4 g/cm³ to 1.6 g/cm³. 91.A SiCHN film containing C═C bonds therein.
 92. A SiCHN film as claimedin claim 91, wherein the SiCHN film has a C/Si composition ratio of 1.0to 1.3.
 93. A SiCHN film as claimed in claim 91, wherein the SiCHN filmhas a density of 1.4 g/cm³ to 1.6 g/cm³.
 94. A semiconductor devicehaving a trench interconnection structure, which comprises: aninterlayer insulating film formed on a semiconductor substrate, a trenchinterconnection formed in the interlayer insulating film, and a barrierinsulating film formed so as to cover over the trench interconnection,wherein the barrier insulating film is formed by using a SiCHN film asclaimed in any one of claims 91-93.
 95. A semiconductor device asclaimed in claim 94, wherein the interlayer insulating film is formed byusing a SiOCH film containing C═C bonds therein.
 96. A semiconductordevice as claimed in claim 94, wherein the barrier insulating film is alayered film made of the SiCHN film and a SiCH film.
 97. A semiconductordevice having a trench interconnection structure, which comprises: aninterlayer insulating film formed on a semiconductor substrate, and atrench interconnection formed in the interlayer insulating film, whereinthe interlayer insulating film is a layered insulating film in which anetching stopper film is included, and the etching stopper film is formedby using a SiCHN film as claimed in any one of claims 91-93.
 98. Asemiconductor device as claimed in claim 97, wherein the interlayerinsulating film is a layered insulating film comprising a SiOCH filmcontaining C═C bonds therein and the etching stopper film.
 99. Asemiconductor device as claimed in claim 97, wherein the etching stopperfilm is a layered film made of the SiCHN film and a SiCH film.
 100. Asemiconductor device having a trench interconnection structure, whichcomprises: a first insulating film formed on a semiconductor substrate,a first trench interconnection formed in the first insulating film, asecond insulating film, a third insulating film, a second trenchinterconnection formed in the third insulating film, and a via plug thatis formed in the second insulating film and connects the first trenchinterconnection and the second trench interconnection, wherein the firstinsulating film is a layered insulating film comprising a SiOCH film andan etching stopper film, and the etching stopper film is formed by usinga SiCHN film as claimed in any one of claims 91-93.
 101. A semiconductordevice having a trench interconnection structure, which comprises: afirst insulating film formed on a semiconductor substrate, a firsttrench interconnection formed in the first insulating film, a secondinsulating film, a third insulating film, a second trenchinterconnection formed in the third insulating film, and a via plug thatis formed in the second insulating film and connects the first trenchinterconnection and the second trench interconnection, wherein thesecond insulating film is a layered insulating film comprising a SiOCHfilm and a barrier insulating film, and the barrier insulating film isformed by using a SiCHN film as claimed in any one of claims 91-93. 102.A semiconductor device having a trench interconnection structure, whichcomprises: a first insulating film formed on a semiconductor substrate,a first trench interconnection formed in the first insulating film, asecond insulating film, a third insulating film, a second trenchinterconnection formed in the third insulating film, and a via plug thatis formed in the second insulating film and connects the first trenchinterconnection and the second trench interconnection, wherein thesecond insulating film is a layered insulating film comprising a SiOCHfilm and an etching stopper film, and the etching stopper film is formedby using a SiCHN film as claimed in any one of claims 91-93.
 103. Asemiconductor device having a trench interconnection structure, whichcomprises: a first insulating film formed on a semiconductor substrate,a first trench interconnection formed in the first insulating film, asecond insulating film, a third insulating film, a second trenchinterconnection formed in the third insulating film, and a via plug thatis formed in the second insulating film and connects the first trenchinterconnection and the second trench interconnection, wherein the thirdinsulating film is a layered insulating film comprising a SiOCH film andan etching stopper film, and the etching stopper film is formed by usinga SiCHN film as claimed in any one of claims 91-93.
 104. A semiconductordevice as claimed in claim 100, wherein the SiOCH film contains C═Cbonds therein.
 105. A semiconductor device as claimed in claim 101,wherein the SiOCH film contains C═C bonds therein.
 106. A semiconductordevice as claimed in claim 102, wherein the SiOCH film contains C═Cbonds therein.
 107. A semiconductor device as claimed in claim 103,wherein the SiOCH film contains C═C bonds therein.